Time delay fuze

ABSTRACT

A time delay fuze for a projectile includes a ball rotor journaled for rotation within a cavity in the fuze. The firing pin, said cavity and the booster charge lie along the longitudinal axis of the fuze. The rotor carries a detonator in a diametral bore, and a dished retaining ring mounted on a seat cut into the ball normally fixes the ball with the detonator out of alignment with the longitudinal axis of the fuze. To release the rotor, the dished ring must be flattened and moved aft by setback force and must be enlarged by centrifugal force.

United States Patent Inventor Appl. No. Filed Patented Assignee TIME DELAY FUZE 2 Claims, 3 Drawing Figs.

US. Cl

lnt.Cl F42: 15/26 Field Search 102/70, 76, 78, 79, 80

References Cited UNITED STATES PATENTS 2/ 1951 Nichols Primary Examiner-Samuel W. Engle AnomeysBailin L, Kuch, lrving M. Freedman, Harry C.

Burgess, Frank L. Neuhauser, Oscar B. Waddell and Joseph B. Forman ABSTRACT: A time delay fuze for a projectile includes a ball rotor joumaled for rotation within a cavity in the fuze. The firing pin, said cavity and the booster charge lie along the iongitudinal axis of the fuze. The rotor carries a detonator in a diametral bore, and a dished retaining ring mounted on a seat cut into the ball normally fixes the ball with the detonator out of alignment with the longitudinal axis of the fuze. To release the rotor, the dished ring must be flattened and moved aft by setback force and must be enlarged by centrifugal force.

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BY /HIS TTORNEY.

INVEHTOR'.

TIME DELAY FUZE BACKGROUNDOF THE INVENTION 1. Field of the Invention This invention is related to time delayed fuzes for ammunition of relatively small calibre.

2. Prior Art The fuze of this invention is an improvement on the fuze shown in my U.S. Pat. No. 3,397,640, issued Aug. 20, I968. In that patent I disclosed a fuze which has a ball rotor supporting and normally disposing a detonator out of alignment with the firing pin and the booster charge, and disposing the detonator in alignment with the firing pin and the booster charge after the application over a predetennined period of time of a predetennined centrifugal force. Specifically, the rotor is held in an out-of-Iine position by means of a rotor detent spring. This spring locks the rotor in an out-of-line position until projectile spin is sufficient to cause the spring to open, thereby releasing the rotor. Once the rotor is free of the spring, it is free to rotate, due to its dynamic mas unbalance, to an in-line position. It is conceivable that projectile with its fuz e might be inadvertently rotated, as by rolling down a ramp in' handling, at a velocity high enough to release the detent spring, arming the fuze. Obviously, such a situation is not desirable.

Accordingly, it is an object of this invention to precondition arming on the simultaneous presence of both adequate spin and setback forces.

SUMMARY OF THE INVENTION A feature of this invention is a time delay fuze for a projectile including a ball rotor journaled for rotation within a cavity in the fuze. The firing pin, said cavity and the booster charge lie along the longitudinal axis of the fuze. The rotor carries a detonator in a diametral bore, and a dished retaining ring mounted on a seat cut into the ball nonnally fixes the ball with the detonator out of alignment with the longitudinal axis of the fuze. To release the rotor, the dished ring must be flattened and moved aft by setback force and must be enlarged by centrifugal force.

BRIEF DESCRIPTION OF THE DRAWING These and other objects, advantages and features of this invention will be apparent from the following specification thereof taken in conjunction with the accompanying drawing in which:

FIG. 1 is a longitudinal cross section of the fuze embodying this invention;

FIG. 2 is a plan view of the dished retaining ring of the fuz of FIG. 1; and

FIG. 3 is an edge view of the ring of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The fuze includes a fuze body of substantially conical shape. The body has a longitudinal bore having an aft portion of relatively large diameter 12 terminating in a medial subportion 14 of hemispherical shape, and a forward portion 16 of relatively small diameter. The aft bore portion is internally threaded to receive a booster housing 18 having a central cavity 20 containing a booster charge 22. A firing pin assembly 24, which may be of the self-destruct type shown in U.S. Pat. No. 3,397,640 supra, is disposed in the forward bore portion, and is covered by a nose cap 26. The forward end of the booster housing has a spherical recess 28 therein, so that, in conjunction with the fuze body bore medial subportion 14, a substantially spherical cavity is formed when the booster housing 18 is screwed into the fuze housing. A ball rotor 30 is disposed within the spherical cavity. A primer assembly 32 is disposed in a diametral bore 34 in the ball rotor. An annular groove 36 is cut into the perimeter of the ball and receives a dished, horseshoe-shaped retaining ring or clip 38. An internal, annular groove is cut into the fuze housing bore adjacent the bore end of the detonator housing.

The clip is dished about a transverse axis A-A running along the plane of symmetry and has a weakened portion 42 lying on the axis opposite the jaws of the horseshoe. When the aft surface of the clip rests on the face of the booster housing, the arced forward edges of the clip are forward of the annular housing groove so thatthe clip cannot directly open into the groove, and flattening of the clip is first necessary.

In use, the ball rotor 30 is held with the detonator 32, in the out-of-line, safe, disposition. When the projectile is fired through the tube of the weapon, the acceleration sets back the clip 40 against the face of the booster housing in a flat configuration, into alignment with the annular housing groove 40. As the projectile passes through the tube it is spun by the rifling in the tube. The clip locks the rotor in the out-of-line disposition until the spin of the rotor and the clip is sufircient to cause the clip to expand into the annular housing groove, thereby releasing the ball rotor. The clip may be made of phosphor bronze, may flatten at 70,000 gs linear acceleration and rupture at neck 42 at about 70,000 r.p.m.

Once the ball rotor is freed of the spring, it is free to rotate, due to dynamic mass unbalance to an in-line armed dispositron.

Should the projectile be rotated without an initial adequate setback to flatten the clip, the clip will not be able to enter the housing groove 40, and will not release the rotor, thereby precluding arming of the fuze.

In an exemplary design, the ball rotor 30 may have a diameter of 0.375 inch, the groove 36 may have a longitudinal height of 0.049 inch, the groove 40 may have an effective longitudinal height of 0.043 inch, the clip 38 may have a longitudinal strip thickness of 0.015 feet, and a longitudinal bulk thickness as dished of 0.060 inch.

What I claim is:

' l. A time delay fuze mechanism having a safed disposition and an armed disposition, for ammunition, comprising:

a housing having a longitudinal axis extending fore and aft,

and a substantially spherical cavity therein which is symmetrical about said axis; a substantially spherical rotor disposed in said cavity having an axis of mass symmetry and a diametral bore coaxial therewith and adapted to receive a detonating charge therein; a first annular groove formed into the periphery of said rotor perpendicular to a first diameter, which first diameter is angularly displaced from said axis of mass symmetry and which first diameter, in the safed disposition, is coaxial with said housing longitudinal axis, to form a protuberance in said rotor extending radially rearwardly; a second annular groove formed into the wall of said housing cavity perpendicular to said housing longitudinal axis, adjacent to the distal, rearward end of said rotor protuberance; and a spring clip disposed on said rotor protuberance,

said spring being of substantially flat, horseshoe shaped, stock disposed transversely on said protuberance, and dished, resiliently longitudinally to provide aft elements of the spring which are in transverse alignment with said second annular groove and forward elements of the spring which are forward of said second annular groove,

whereby said spring normally engages said protuberance and abuts the wall of said housing cavity and precludes rotation of said rotor within said cavity; and

whereby said spring is adapted, upon the application of an adequate setback force to flatten'out so that its forward elements move aft into alignment with said second annular groove, and when in said flattened out disposition, upon the application of an adequate centrifugal force, to expand into said second annular groove to free said rotor for rotation within said cavity into said armed disposition.

2. A mechanism accordingto claim l whereinr said horseshoe-shaped spring has a medial reduction in cross section, whereby upon the application of adequate centrifugal force, said spring ruptures at said reduction. 

1. A time delay fuze mechanism having a safed disposition and an armed disposition, for ammunition, comprising: a housing having a longitudinal axis extending fore and aft, and a substantially spherical cavity therein which is symmetrical about said axis; a substantially spherical rotor disposed in said cavity having an axis of mass symmetry and a diametral bore coaxial therewith and adapted to receive a detonating charge therein; a first annular groove formed into the periphery of said rotor perpendicular to a first diameter, which first diameter is angularly displaced from said axis of mass symmetry and which first diameter, in the safed disposition, is coaxial with said housing longitudinal axis, to form a protuberance in said rotor extending radially rearwardly; a second annular groove formed into the wall of said housing cavity perpendicular to said housing longitudinal axis, adjacent to the distal, rearward end of said rotor protuberance; and a spring clip disposed on said rotor protuberance, said spring being of substantially flat, horseshoe shaped, stock disposed transversely on said protuberance, and dished, resiliently lonGitudinally to provide aft elements of the spring which are in transverse alignment with said second annular groove and forward elements of the spring which are forward of said second annular groove, whereby said spring normally engages said protuberance and abuts the wall of said housing cavity and precludes rotation of said rotor within said cavity; and whereby said spring is adapted, upon the application of an adequate setback force to flatten out so that its forward elements move aft into alignment with said second annular groove, and when in said flattened out disposition, upon the application of an adequate centrifugal force, to expand into said second annular groove to free said rotor for rotation within said cavity into said armed disposition.
 2. A mechanism according to claim 1 wherein: said horseshoe-shaped spring has a medial reduction in cross section, whereby upon the application of adequate centrifugal force, said spring ruptures at said reduction. 